3IO OF THE GROWTH, &c. 



dud of fecundation, refulting from the mixture 

 of the male and female femen. To afcertaia 

 this fadV, feveral things require attention : When 

 the hen has, for fome days, been along with the 

 cock, and afterwards feparated from him, the 

 eggs produced 20 days or a month after this fe- 

 paration, are equally fertile as thofe laid during 

 her cohabitation with the male. The eggs pro- 

 duced at the end of this period require only the 

 ufual time of 21 days in hatching ; and their 

 embryos are equally advanced both in form and 

 confiftence. From this circumftance we might 

 be led to imagine, that the form in which the 

 embryo appears before incubation, is not the 

 immediate effect of the mixture of the two fe- 

 minal fluids, but that it exifted in different 

 forms during the abode of the egg in the body 

 of the mother ; for the embryo, in the form in 

 "which we fee it before incubation, requires only 

 the aid of heat in order to bring it to maturity. 

 Now, if this form of tlie embryo had exifted 

 2 1 d^ys or a month before, when the egg was 

 firR impregm^ted, why was it not hatched by the 

 internal heat of the mother \ Why do we not 

 tind the chick com.pletely formed in thofe eggs 

 which have been impregnated 21 days before 

 they are laid \ 



But this (lifliculty, though feemingly great, is 

 r.ot infurmountahle. When the hen cohabits 

 with the cock, the cicatrice of each egg, which 

 cantains tlie fcmcn of the female, receives a fmall 



quantity 



